Identification of Possible Artifacts in the Association of Official Analytical Chemists Sporicidal Test

Two laboratories tested four different brands of alkaline 2% glutaraldehyde sterilants by the Association of Official Analytical Chemists sporicidal test. Each laboratory found survival of Clostridium sporogenes spores on spore-labeled unglazed porcelain penicylinders (cylinders) to vary from test to test, and survival did not always correlate with increasing sterilant exposure time. These results were consistent with a theory that there may be random conditions within the test that prevent the sterilant from contacting all spores. Further studies indicated that the prior history of the unglazed porcelain cylinders and whether the C. sporogenes culture grown in egg-meat media had been processed (homogenized) to eliminate visible pieces of egg-meat media were important factors affecting the results and repeatability of this test.     

The relationship between serial monogamy and rape in the United States (1960-1995)

In mating systems where individuals pair, separate and re-pair repeatedly (i.e. serial monogamy), some males monopolize more than one female's reproductive life span and thus leave other males effectively mateless. Males who cannot secure females through traditional methods may seek alternatives, such as rape, to ensure gene passage into future generations. Analysis of US government records shows that (i) divorce and remarriage patterns in the United States are likely to increase the variance in male reproductive success, and (ii) rates of divorce and rape correlate positively. The former result suggests that serial monogamy increases the variance in male, relative to female, reproductive success and the latter result suggests that this variance influences the frequency of rape in American society. Because raped females sometimes become pregnant and take these pregnancies to term, our results indicate that rape has current adaptive significance.     

A novel 'sit and wait' reproductive strategy in social wasps

I present evidence indicating that a subset of spring females in the social wasp Polistes dominulus do not initiate colonies but rather ''sit and wait'' to adopt colonies initiated and abandoned by other conspecifics. These results are, to my knowledge, the first to demonstrate conclusively this alternative reproductive strategy in social wasps. Individuals engaging in the sit-and-wait strategy behave selfishly by adopting the most mature nests available; such nests will produce workers sooner than less mature nests and, consequently, are more likely to survive. The sit-and-wait reproductive strategy may safeguard an individual from early-season, foraging-related mortality as well as reduce early-season energy expenditure.     

Regulation of Insulin Receptor Trafficking by Bardet Biedl Syndrome Proteins

Insulin and its receptor are critical for the regulation of metabolic functions, but the mechanisms underlying insulin receptor (IR) trafficking to the plasma membrane are not well understood. Here, we show that Bardet Biedl Syndrome (BBS) proteins are necessary for IR localization to the cell surface. We demonstrate that the IR interacts physically with BBS proteins, and reducing the expression of BBS proteins perturbs IR expression in the cell surface. We show the consequence of disrupting BBS proteins for whole body insulin action and glucose metabolism using mice lacking different BBS genes. These findings demonstrate the importance of BBS proteins in underlying IR cell surface expression. Our data identify defects in trafficking and localization of the IR as a novel mechanism accounting for the insulin resistance commonly associated with human BBS. This is supported by the reduced surface expression of the IR in fibroblasts derived from patients bearing the M390R mutation in the BBS1 gene.     

Discovery and characterization of single nucleotide polymorphisms in Chinook salmon, Oncorhynchus tshawytscha

Molecular population genetics of non-model organisms has been dominated by the use of microsatellite loci over the last two decades. The availability of extensive genomic resources for many species is contributing to a transition to the use of single nucleotide polymorphisms (SNPs) for the study of many natural populations. Here we describe the discovery of a large number of SNPs in Chinook salmon, one of the world's most important fishery species, through large-scale Sanger sequencing of expressed sequence tag (EST) regions. More than 3 Mb of sequence was collected in a survey of variation in almost 132 kb of unique genic regions, from 225 separate ESTs, in a diverse ascertainment panel of 24 salmon. This survey yielded 117 TaqMan (5' nuclease) assays, almost all from separate ESTs, which were validated in population samples from five major stocks of salmon from the three largest basins on the Pacific coast of the contiguous United States: the Sacramento, Klamath and Columbia Rivers. The proportion of these loci that was variable in each of these stocks ranged from 86.3% to 90.6% and the mean minor allele frequency ranged from 0.194 to 0.236. There was substantial differentiation between populations with these markers, with a mean F(ST) estimate of 0.107, and values for individual loci ranging from 0 to 0.592. This substantial polymorphism and population-specific differentiation indicates that these markers will be broadly useful, including for both pedigree reconstruction and genetic stock identification applications.     

Use of a marker plasmid to examine differential rates of growth and death between clinical and environmental strains of Vibrio vulnificus in experimentally infected mice

Vibrio vulnificus is Gram-negative bacterium that contaminates oysters, causing highly lethal sepsis after consumption of raw oysters and wound infection. We previously described two sets of V. vulnificus strains with different levels of virulence in subcutaneously inoculated iron dextran-treated mice. Both virulent, clinical strains and attenuated, environmental strains could be recovered in high numbers from skin lesions and livers; however, the attenuated environmental strains required significantly higher numbers of colony-forming units (cfu) in the inoculum to produce lethal infection. Using some of these strains and an additional clinical strain, we presently asked if the different abilities to cause infection between the clinical and environmental strains were due to differences in rates of growth or death of the bacteria in the mouse host. We therefore constructed a marker plasmid, pGTR902, that functions as a replicon only in the presence of arabinose, which is not present in significant levels in animal tissues. V. vulnificus strains containing pGTR902 were inoculated into iron dextran-treated and untreated mice. Measuring the proportion of bacteria that had maintained the marker plasmid recovered from mice enabled us to monitor the number of in vivo divisions, hence growth rate; whereas measuring the number of marker plasmid-containing bacteria recovered enabled the measurement of death of the vibrios in the mice. The numbers of bacterial divisions in vivo for all of the strains over a 12-15 h infection period were not significantly different in iron dextran-treated mice; however, the rate of death of one environmental strain was significantly higher compared with the clinical strains. Infection of non-iron dextran-treated mice with clinical strains demonstrated that the greatest effect of iron dextran-treatment was increased growth rate, while one clinical strain also experienced increased death in untreated mice. V. vulnificus inoculated into iron dextran-treated mice replicated extremely rapidly over the first 4 h of infection with doubling times of approximately 15-28 min. In contrast, one of the environmental strains exhibited a reduced early growth rate. These results demonstrate that differences in virulence among naturally occurring V. vulnificus can be explained by diverse abilities to replicate rapidly in or resist defences of the host. The marker plasmid pGTR902 should be useful for examining virulence of bacteria in terms of differentiating growth verses death in animal hosts for most Gram-negative bacteria.     

Within- and across-colony effects of hyperpolyandry on immune function and body condition in honey bees (Apis mellifera)

Honey bees (Apis mellifera) have become a model system for studies on the influence of genetic diversity on disease. Honey bee queens mate with a remarkably high number of males-up to 29 in the current study-from which they produce a colony of genetically diverse daughter workers. Recent evidence suggests a significant benefit of intracolony genetic diversity on disease resistance. Here, we explored the relationship between the level of genetic diversity and multiple physiological mechanisms of cellular and humoral immune defense (encapsulation response and phenoloxidase activity). We also investigated an effect of genetic diversity on a measure of body condition (fat body mass). While we predicted that mean colony phenoloxidase activity, encapsulation response, and fat body mass would show a positive relationship with increased intracolonial genetic diversity, we found no significant relationship between genetic diversity and these immune measures, and found no consistent effect on body condition. These results suggest that high genetic diversity as a result of extreme polyandry may have little bearing on the physiological mechanisms of immune function at naturally occurring mating levels in honey bees.     

The ontogeny of immunity: development of innate immune strength in the honey bee (Apis mellifera)

Honey bees (Apis mellifera) are of vital economic and ecological importance. These eusocial animals display temporal polyethism, which is an age-driven division of labor. Younger adult bees remain in the hive and tend to developing brood, while older adult bees forage for pollen and nectar to feed the colony. As honey bees mature, the types of pathogens they experience also change. As such, pathogen pressure may affect bees differently throughout their lifespan. We provide the first direct tests of honey bee innate immune strength across developmental stages. We investigated immune strength across four developmental stages: larvae, pupae, nurses (1-day-old adults), and foragers (22-30 days old adults). The immune strength of honey bees was quantified using standard immunocompetence assays: total hemocyte count, encapsulation response, fat body quantification, and phenoloxidase activity. Larvae and pupae had the highest total hemocyte counts, while there was no difference in encapsulation response between developmental stages. Nurses had more fat body mass than foragers, while phenoloxidase activity increased directly with honey bee development. Immune strength was most vigorous in older, foraging bees and weakest in young bees. Importantly, we found that adult honey bees do not abandon cellular immunocompetence as has recently been proposed. Induced shifts in behavioral roles may increase a colony's susceptibility to disease if nurses begin foraging activity prematurely.     

Intersexual Conflict and Group Size in <Emphasis Type="Italic">Alouatta palliata</Emphasis>: A 23-year Evaluation

Models of optimal primate group size suggest that group formation and growth arise to benefit individual fitness, but that size is limited by costs. The ecological constraints hypothesis posits that group formation and growth is driven by protection from predation or the advantages of group foraging, while an upper limit on group size is constrained by travel costs and intragroup competition for food or other critical resources. Socioecological models also predict that individual reproductive success, hypothesized to decrease with increasing group size, also places an upper limit on the number of individuals in a group. Our analysis of 23 yr of group composition data on mantled howlers (Alouatta palliata) from a single Panamanian study site on Barro Colorado Island not only corroborates the socioecological model but also shows that female reproductive success increased, whereas that of males decreased, with the less female-biased sex ratios in larger groups. We suggest that the conflict of interest between the sexes over adult sex ratio, particularly the male proportion in a group, in combination with ecological factors, is an important determinant of group size and composition.